The present invention relates to a cable tie for crossing intersecting cables and more particularly to a permanent cable tie for crossing intersecting cables in an air supported structure cable net.
Air supported structures are known. These structures include a sheet-like member inflatable on a surface upon which the air supported structure is to be erected. When the sheet-like member is in an inflated condition the air supported structure has a shape defined by the shape of the sheet-like member.
It is known to reinforce an air supported structure by disposing a network of cables over the structure. The cable network lies on the air supported structure and is comprised of a plurality of crossing cables which are anchored around the periphery of the air supported structure to the surface on which the air supported structure is erected. An example of an inflatable structure reinforced by a cable network is found in U.S. Pat. No. 3,885,360.
Cable networks for air supported structures are held in shape by cable clamps which clamp the cables comprising the net together at their points of crossing. It is necessary to clamp the cables together in order to maintain the shape of the cable net during inflation of the air supported structure. An example of such a cable clamp is found in U.S. Pat. No. 3,903,574.
The cable clamps presently used for air inflatable structure cable nets have various features which would be desirable to improve. First, the cable clamps have an irregular shape and are fabricated by machining them from a piece of metallic stock. The machining operation and the irregular shape of them contributes to their cost. Although the machining costs can be alleviated somewhat by using castings in the shape of the cable clamp, the cable clamps would still be relatively expensive.
Secondly, the irregular shape of the cable clamps contributes to wear of the air structure. The cable clamps rest on the air structure surface and movement of the air structure relative to the cable clamps, caused for example, by wind, causes wear in the region of the cable clamps.
Thirdly, the cable clamps are relatively difficult to install at the time a cable net is made up. The cables used with air supported structures are generally multistrand metal cables covered by a plastic sheath such as vinyl. In order to get a tight grip on the cables it is necessary to cut back the plastic sheath at the point where the cable clamp is to be attached to the cables. This operation is time consuming. Furthermore, cutting the plastic sheath allows water to enter into the cable and rust the inner metallic strands. Rust stains consequently appear on the air supported structure surface and the cables themselves deteriorate. Additionally, rusted cable surfaces against the air supported structure will chafe the material comprising the sheet-like member of the air structure.
The prior art cable clamps have also been used by connecting them directly over the plastic cable sheath instead of cutting the sheath back to allow the cable clamp to connect to the metal cable directly. This technique has been unsuccessful since the clamp over the plastic cable sheath has a tendency to grip the sheath without establishing a mechanical connection through the sheath with the metal cable strands. As a consequence, forces applied to the cable sheath by the cable clamps cause portions of the cable sheath to strip away and expose the metal cable strands.